Various controlled acceptance mailing systems have been developed such as those disclosed in U.S. patent application Ser. No. 432,733 filed May 2, 1995, for Cordery and Pintsov, entitled CONTROLLED ACCEPTANCE MAIL PAYMENT AND EVIDENCING SYSTEM, now U.S. Pat. No. 5,675,650 Additionally, other controlled acceptance systems have been developed such as those shown in U.S. patent application Ser. No. 665,268 filed Jun. 17, 1996, for Cordery and Pintsov and Weiant, now entitled CONTROLLED ACCEPTANCE MAIL SYSTEM SECURELY ENABLING REUSE OF DIGITAL TOKEN INITIALLY GENERATED FOR A MAIL PIECE ON A SUBSEQUENTLY PREPARED DIFFERENCE MAIL PIECE TO AUTHENTICATE PAYMENT OF POSTAGE, now U.S. Pat. No. 5,768,132. The entire disclosure of these two patent applications and the issued patent are hereby incorporated by reference. Various methods for handling cryptographic key are disclosed in U.S. Pat. No. 4,935,961, for METHOD AND APPARATUS FOR GENERATION AND SYNCHRONIZATION OF CRYPTOGRAPHIC KEYS and in U.S. Pat. No. 4,853,961 for RELIABLE AUTHENTICATION SYSTEM.
In controlled acceptance systems, batches of mail are brought to a carrier service such as a postal carrier service for mail processing. The mail is brought along with a statement of mailing to tie the batch of mail together with a document used by the carrier service to help verify payment of postage or carrier for the batch of mail.
The controlled acceptance systems may involve the printing of encrypted indicias. The encrypted indicias can employ a digital token. The digital token is encrypted data that authenticates the value and other information printed on the mail piece. Examples of systems for generating and using digital tokens are described in U.S. Pat. No. 4,757,537 for SYSTEM FOR DETECTING UNACCOUNTED FOR PRINTING IN A VALUE PRINTING SYSTEM; U.S. Pat. No. 4,831,555 for UNSECURED POSTAGE APPLYING SYSTEM; and U.S. Pat. No. 4,775,246 for SYSTEM FOR DETECTING UNACCOUNTED FOR PRINTING IN A VALUE PRINTING SYSTEM. Because the digital token incorporates encrypted data including postage value, altering of the printed postage revenue and the postage revenue block is detectable by a standard verification procedure.